Earliest eligible virtual deadline first scheduling

Earliest eligible virtual deadline first (EEVDF) is a dynamic priority proportional share scheduling algorithm for soft real-time systems.^[1]

Algorithm

EEVDF was first described in the 1995 paper "Earliest Eligible Virtual Deadline First : A Flexible and Accurate Mechanism for Proportional Share Resource Allocation" by Ion Stoica and Hussein Abdel-Wahab.^[2] It uses notions of virtual time, eligible time, virtual requests and virtual deadlines for determining scheduling priority.^[1] It has the property that when a job keeps requesting service, the amount of service obtained is always within the maximum quantum size of what it is entitled.^[3]

Linux kernel scheduler

See also: Linux kernel § Scheduling

In 2023, Peter Zijlstra proposed replacing the Completely Fair Scheduler (CFS) in the Linux kernel with an EEVDF process scheduler.^[4][5] The aim was to remove the need for CFS "latency nice" patches.^[6] The EEVDF scheduler replaced CFS in version 6.6 of the Linux kernel.^[7]

See also

• Brain Fuck Scheduler
• Earliest deadline first scheduling (EDF)
• nice (Unix)
• SCHED_DEADLINE

References

1. Erickson, Jeremy P.; Anderson, James H. (September 2, 2022). Tian, Yu-Chu; Levy, David Charles (eds.). Handbook of Real-Time Computing. Springer Nature. pp. 233–267. doi:10.1007/978-981-287-251-7_4 – via Springer Link.
2. Stoica, Ion; M. Abdel-Wahab, Hussein (1995). Earliest Eligible Virtual Deadline First : A Flexible and Accurate Mechanism for Proportional Share Resource Allocation (Technical report). CS Dpt., Old Dominion Univ. TR-95-22.
3. Epema, D. H. J. (November 2, 1998). "Decay-usage scheduling in multiprocessors". ACM Transactions on Computer Systems. 16 (4): 367–415. doi:10.1145/292523.292535.
4. "EEVDF Scheduler May Be Ready For Landing With Linux 6.6". Phoronix. Retrieved 2023-08-31.
5. "[PATCH 00/10] sched: EEVDF using latency-nice [LWN.net]". LWN.net.
6. "An EEVDF CPU scheduler for Linux [LWN.net]". LWN.net. Retrieved 2023-08-31.
7. "EEVDF Scheduler Merged For Linux 6.6, Intel Hybrid Cluster Scheduling Re-Introduced". Phoronix.